Lathe.



C. G. BARTH.

LATHE.

APPLICATION FILED SEPT. I4. 1916- Patented May15,1917.

3 SHEETS-SHEET l.

INVENTOR ('arl Gfiarlii "f mam H T TORNE Y C. G. BARTH.

LATHE.

APPLICATION FILED SEPT. 14. 1916.

3 SHEETS-SHEET 2.

ATTORNEY C. G. BARTH.

LATHE.

v APPLICATION FILED SEPT. 14. 19l6.

3 SHEETS-SHEET 3.

E? Z v i 1 6 IN VE N TOR A T'TORNE Y Patented May 15, 1917.

- this latter, which project into suitable slots 40 the two tails of the dog do not initially get animate AT.

- cam; o. Burn, or PHILAD PHIA, PENNSYLVANIA.

LATE.

. Specification of Letters Patent. I

To all whom it ma 00mm:

Be it known that I, CARL G.-BARTH, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia, Statev of' Pennsylvania,- have invented a new -and useful Lathe, of'whichthe following is a specification.

. My invention relates to improvements in lathes, and theobject is to provide improved means for driving the work. The invention is particularly adapted for axle lathes, and

. especially double ended axle lathes, in which the driving head is in the middle of the lathe, and the axle rotates on a stationary center in a tail stock at each end of'the lathe bed, and tool carriages are operated at both sides of the driving head.

As is well known, the practice is, in connection with such lathes to rovide between the face plate of the drivlng head and a double-ended clamping dog, a so-called equalizing plate, for equalizing the driving pressure on the two ends 'or' tails of this dog, with a view to moresteady,-or chatterless motion -of the'axle under cut. To this end this plate is provided with oppositely disposed lugs adapted to engage the opposite tails of the dog, while this equalizing plate is itself mounted on and driven by the face plate, by means of other lugs, on

in contact with their respective driving lugs on the plate at the same time, or with equal pressure.

However, the weight (gravity) of this equalizing plate enters into 1ts theoretical and intended action,.as just described, as

a decidedly disturbing factor, which, when lighter cuts are taken, such asthe finishing cuts on the wheel fit and on the ournals of an axle, not only absolutely destroys its intended equalizing action, but even pro duces a most detrimental hammering action,

twice in every revolution of the lathe.

An attempt to overcome this disadvan- Patented May 15, 1917.

' Application filed September 14,191 Serial in. 120,019.

tage has been made by applicant, which consists in providing spring-washers to press the equalizing plate against the face plate, and thusto create a certain amount-of fric tion that would check this gravity hammering of the equalizing plate. However, due to the difliculty, not to say impossibility,

of adjusting the pressure of such sprlng washer to a nicety, these almost invariably produce either more than the desirable amount of friction between the equalizing plate and the face plate, or else not enough. In the former case the equalizing tendency is almost or Wholly neutralized, in the latter. case the hammering effect under light out is only lessened and not destroyed.

In practice the operator overcomes this by producing an increased'amount of resistance to the rotation of the axle, by tightening the same unduly between the centers of the lathe, which underthe high speeds of rotation of to-day results in the frequent burning out of these centers.

Thus recognizing that these troubles are due to the gravity of the alleged, equalizing plate on the one hand, and on the other hand ,to the lack of suflicient flexibility in the adjustment of the spring washers provided by the builders, my first attempt to overcome these troubles consisted in merely lightening the equalizing plate to the greatest extent consistent with strength, together with providing ordinary retaining washers to hold the equalizing plate. against the face plate under the pressure of helical springs that readily could be-adjusted to exert any desired pressure on these washers, however, without any attempt to change the general constructive features of the whole arrangement.

But while this greatly, and to a very encouraging degree, reduced these troubles, it did not wholly eliminate them, and my in- I vention, now to be described, consists in the adoption of certain modifying constructive 'features of the arrangement that enables the equalizing plate, -.or' rather equalizing frame as I nowimakeit, to be made so light, and still adequately] strongthat the disturbing influence of its remaining weight is no longer of any practical consequence. As will appear from this description, I have also attained certain other advantages over the customary construction.

Referring tothe drawings, which illustrate, merely by way of example, suitable embodiments of my invention- Figure 1 is a front elevation of a standard axle lathe to which my invention in part is applied.

Fig. 2 is a sectional elevation on line 2-2 of Fig. 1, on an enlarged scale, and showing modified lugs 9.

Fig. 3 is a section on line 33 of Fig. 2.

Fig. 4 is a front elevation of a driving head, embodying my principal invention.

Fig. 5 is a side elevation of same.

Fig. 6 is a section on line 6-6 of Fig. 4.

Fig. 7 is a detail on an enlarged scale, showing a ball and socket connection.

Fig. 8 is asimilar view but in part section, showing a modification.

Fig. 9 is a section on line 99 of Fig. 4, but on an enlarged scale.

Fig. 10 is a section on line 10-10 of 7.

Fig. 11 is a fragmentary view in elevation of a modification of the equalizing frame.

Fig. 12 is a section on the line 12-12 of Fig. 11. a

. Figs. 13 and 14 are Views in cross section of a modification in cross section.

Similar numerals refer to similar parts throughout the several views.

Referring to Figs. 1, 2 and 3, 1 is the face plate provided with the usual gear 2. This face plate carries the studs '3 provided with rectangular blocks 4 which are received in the oppositely disposed slots or recesses 5, of the equalizing plate 6, so that this equalizing plate 6 may have a limited movement with respect to the face plate 1. The dog 7 is provided at opposite ends with the tails 8 which are adapted to engage the oppositely disposed lugs 9 on the equalizing plate. The lugs 9 are shown as integral projections from plate 6, in Fig. 1, and as pins set in theplate, in Fig. 2. The dog 7 is provided with the jaws 10 and 11; the latter being actuated by the set screws 12 for clamping theaxle 13. As is well understoodin the art as already, indicated, the slight movement of the equalizing plate with respect to the face plate, due to the block and recess connection described, permits an equalization of the pressures between the opposite tails of the dog and the lugs 9 on the equalizing plate. The objection has been, however that, due to the weight of the equalizing plate, as indicated in Fig. 1, a

disturbing factor of gravity enters in in that whenever the oppositely disposed slots 5 assume the vertical position as shown in Fig. 2, there is a tendency for the equalizing plate to fall. due to the force of gravity, and this causes chattering. *To overcome this, as above stated, spring washers were used with unsatisfactory results. I have found however, that by using a helical spring 14 operating between adjustable nuts 15 and an ordinary washer 16, the required pressure of the spring 14 exerted on the washer 16 is secured by the adjustment of nuts 15. Thus the friction between the face plate and the equalizing plate may be so nicely adjusted as largely to obviate the disturbing factor of gravity, without seriously effecting the equalizing action, except for very light cuts. When the weight of the equalizing plate is very greatly reduced, which is made possible by my special construction, this disturbing factor is reduced to such an extent, that practical perfection is obtained.

In Figs. 4, 5 and 6, I show an equalizing frame of different construction from that of the equalizing plate shown iii Fig. 1. It is in the form of a rectangular frame of I beam structure, still having the oppositely disposed slots for receiving the blocks and studs connected with the face plate.

The dog 21 is provided at opposite sides with projections or elements connected thereto, forming, with the blocks 22, seated in oppositely disposed recesses in the equalizing frame 20, movable connections between the dog and the equalizing frame. In Fig. 7 the connection between the equalizing frame and the dog is shown as a ball-andsocket joint, the ball 23 being connected by a tapered connection with dog 21, while a socket is formed in the split block 22 movably seated in the channel or slot 24 of the equalizing frame 20. It will be noted that this block 22 is movable toward and away from the face plate 1, its movement away from the face plate being limited by the flange plate 25; it also has a movement toward and away from the axis of rotation of the head.

In Fig. 8 a modification is shown in that this connection is a hinge connection.

In Fig. 9 is shown a spring pressed washer operating on the stud 3 and engaging the face of equalizing frame 20. The helical spring 14, may be compressed to any desired tension against the washer 16, by means of the nuts 15.

In connection with the dog 21 are provided the movable jaws 28 and.29, the jaw 28 is mounted on the projections or lugs 30 and has engaging surfaces 31. for engaging the lower side of the axle 32. Jaw 29 has corresponding surfaces 33 for engaging the upper side of the axle 32, and the upper side of jaw 29 is engaged by the set screws 34,

Fig. 13 shows in cross-section such exteni sion in form of a solid rod, while in Fig. 14

it is shown in form of a hollow square beam. Y

The operation of the device containing my complete invention is as follows Fig. 4 shows the device in the initial position, or the position in which the axle to be operated upon, is inserted through the head.

Before engaging the dog with the axle, the

dog is in its lower or depressed position, that is with the top of the lower slot 24 resting upon the block 22. While in this position the axle is secured on the centering points of the lathe, and there. will be suflicient space for placing the jaw 28 upon the lugs '30 with the surfaces 31 disengaged from said axle 32. The jaw 29 is now brought in place above the axle and beneath the screws 34, and the screws are now operated until the jaw 29 is exerting pressure on axle 32. As this pressure increases, the dog 21 and jaw 28 are elevated until dog 28 engages axle 32 and until the required clamping pressure is exerted by the said jaws upon the said axle, whereupon the blocks 22 will both assume positions about midway the slots 24.

Since the dog 21 is clamped rigidly to the work to be operated upon, it is immaterial how heavy this may be, since there is no difficulty in making it sufliciently strong.

It is important, as we have seen, that the equalizing frame be able to move slightly with respect to the face plate and also with respect to the dog, in response to unequal pressure already referred to, so as to equalize this pressure again, since the dog is rigid with the work when clamped thereto, and the work is fixed in the centering points.

It is important, as already pointed out, that this equalizing frame, while having a slight movement with respect to the face plate, for the purpose of equalizing pressure, should not be seriously affected by the action of gravity. For this purpose, as already stated, the structure is made sufficiently rigid but of minimum weight.

This reduction of weight without sacrificing the required strength is made posslble by the method .of connecting the dog. to

the frame, that is to say, the dog has, what might be termed, bent-in connections with the equalizin frame; that is, its points ofconnection with the equalizing frame are in a plane different from its points of connections with the work. The equalizing frame, however, has its points of connection with the face plate and its points of connection with. the dog, all in the same plane, so that the main strains to which the equalizing frame is subjected, are strains of compression and of tension in straight lines between the studs 3 and the ball and socket connections 22 and 23, or the corresponding hinge connection of Fig. 8, thesebeingthe strains to which the structure is adapted most adequately to stand.

efficient by the use of the spring pressed 1 Moreover the apparatus 1s made still more washers 16, operating between-the studs 3 and the face of the equalizing frame 20.- The pressure exerted by the helical spring 14, by the adjustment of nuts 15, is just .suf-' ficient to counteract the tendency of the equalizing frame 20 to respond to the action of gravity, when the channels .19 assume the vertical position, and yet not suflicient seriously to interfere with the equalizing movement of the frame as described.

Another purpose of the movable connection between the dog and the equalizing frame "is to permit the dog to swing into a position slightly inclined to the plane of the face plate to facilitate the insertion of the axle through the head in bringing the same into position to be operated upon.

What I claim is 1. In a lathe having the usual head, a face plate, and a dog, the combination of an equalizing plate having limited movable connections with the face plate and with the dog, and means for causing yielding frictional engagement between the equalizing plate and the face plate. y

2. In a lathe having the usual head, a face plate, 'and a dog, the combination of an,

pressure exerted by the springs.

- 4. In a lathe having-the usual head, a fa-ce plate and a dog, the combination of an equalizing frame having limited movable connections with the face plate and with the dog, the said fraine-and the points of said connections all bein in the same plane.

5. In a lathe havmg the usual head, face'i' plate, and dog, the'combination of an equalizing frame having limited movable connections with the faceplate and-with the dog, the points of said connections all being in the same plane, so arranged that the main strains to which the equalizing plate is subjected are strains of compression and of tension in straight lines in the same plane.

6. In a lathe having the usual head, face plate, and dog, the combination of an equalizing frame having limited movable connections with the face plate and with the dog, the points of said connections all being in the same plane, and spring pressed friction means, effective between the face plate and equalizing frame, to counteract tendency to gravity actuation of the equalizing plate.

7. In a lathe having the usual head, face plate, and dog, the combination of an equalizing frame having limited movable connections with the face plate and with the dog, the points of said connections all being in the same plane, and adjustable helical spring pressed friction means effective between the face plate and equaiizing frame, to counteract tendency to gravity actuation of the equalizing frame.

8. In a lathe having the usual head, face plate, and dog, the combinationof an equalizing. frame made of I-beam structure, having limited movable connections with the face plate and with thevdog, the points of said connections all being in the same plane.

9. In a lathe having the usual head, face plate, and dog, the combination of an equalizing frame made of I-beam structure with the web portion recessed atv intervals throughout its extension, having limited movable connections with the face plate and with the dog, the points of said connections all being inthe same plane.

10. In a lathe having the usual head, face plate, and dog, the combination of an equal and limited movable connections with the dog, the points of said connections all being in the same plane. a

11. In a lathe having the usual head, face plate, and dog, the combination of an equalizing frame having limited movable connections with the face plate and ball and socket connections with the dog, the points of said connections all being in the same plane 12. In a lathe having the usual head, face plate, and dog, the combination of an equalizing frame having limited movable connections with the face plate and sliding block and ball and socket connections with the dog, the points of said connections all being in the same plane.

13. In a lathe havingv the usual head, face plate, and dog, the combination of an equalizing frame having limited movable connections with the face plate and with the dog, the points of said connections all being in the same plane, the dog provided with re-v movable clamping jaws.

, 14. In a lathe having the usual head, face plate, and dog, the combination of an equalizing frame having limited movable connections with the face plate and with the dog, the points of said connections all being in the same plane, the dog provided with removable clamping jaws and tension screws cooperating therewith.

15. In a lathe having the usual head, faceplate and dog, the combination of an equal izing frame having limited movable connections with the face-plate and with the dog, said movable connections being such that the .mainf strains to which the equalizing frame is" subjected are strains of compression and tension in a common plane. izing frame having limited movable stud Y and recess connections with theface plate CARL e. EARTH.- 

